• 천문학논총
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• 제5권1호
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• pp.65-84
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• 1990

The temperature effects of the KNU UBV photometric system are investigated, using the HAMAMATSU 1P21 data. The variation of the passband width of V-band with temperature is about $5{\AA}/^{\circ}C$ while those of B-band and U-band are negligible. This large effect of V-band causes a significant variation of V-mag. and (B-V)-color with temperature such as ${\sim}0.02mag/^{\circ}C$ in both cases. This result strongly suggests that in the photometric observations of binary stars, the temperature effects of the response of photomultiplier and the passband of filters must be considered to avoid the systematic variation in magnitude and color particularly at the minimum of light curve.

• 천문학회보
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• 제43권1호
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• pp.49.2-49.2
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• 2018

Flux calibration for narrow band photometric data gives us an opportunity to get a line flux of extended targets. We developed flux calibration processes for narrow band photometry using broad band filters as a continuum indicator. We derived parameters for color correction and zero point correction including color terms. Applying our method, we successfully subtracted continuum emissions and calibrated the emission lines from an FU Ori type object, V960 Mon.

• Current Photovoltaic Research
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• 제11권2호
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• pp.49-53
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• 2023

Expanding the supply of BIPV is crucial to strengthening the competitiveness of the photovoltaic industry and achieving Nationally Determined Contributions through the zero-energy building mandatory policy. BIPV is a technology that integrates into the building envelope to generate electricity and provide functions as a building material. It is suitable for domestic environments with many high-rise buildings due to the narrow land area and urbanization. To expand the supply of BIPV, economics, safety, and aesthetics must be ensured. In this study, a color BIPV module with a color PET film applied as a front material was manufactured for aesthetic and economic feasibility. The relationship between power output and transmittance according to color was analyzed. By analyzing the power output of the module and the transmittance of the film, the wavelength band (transmittance reduction band) that has the greatest effect on efficiency was analyzed regarding the color of the film. The red film showed the narrowest transmittance reduction band and the lowest degree of decrease in transmittance, making it ideal for minimizing the efficiency decrease rate compared to existing ones.

• 한국멀티미디어학회논문지
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• 제4권1호
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• pp.37-45
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• 2001

다대역(multi-band) 카메라 시스템으로 물체의 분광 반사율을 추정하여 피사체의 고유한 색자극을 기록하기 위한 연구가 활발하다. 그러나 다대역 카메라 시스템은 대역 수에 따라 추가적인 색필터가 필요하며 중복촬영으로 인하여 시스템의 복잡성이 증가하는 단점이 있다. 따라서 본 논문에서는 기존의 3대역 RGB 카메라를 이용하여 분광 반사율의 추정 오차를 개선하는 방법을 제안한다. 제안된 방법에서는 화소 단위로 반사광의 모집단을 갱신하여 각 입력색에 대해 적응적인 주성분 벡터를 구하였으며 이를 이용하여 해당 화소의 분광반사율 추정시 오차를 줄였다. 제안된 반사율 추정 방법의 유용성을 평가하기 위하여 제안된 방법과 3대역 주성분 분석(principal component analysis) 방법 및 5대역 위너 추정(Wiener estimation) 방법에 대하여 각각 Macbeth ColorChecker에 대한 분광 반사율 추정 실험을 하였다. 결과, 제안한 방법은 색차 및 분광 반사율 평균자승오차가 기존의 3대역 주성분 분석 방법보다 적었으며 5대역 카메라를 이용한 분광 반사율 추정 방법과 근사하건, 개선되었음을 확인하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1100-1102
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• 2006

A three-band white LED was fabricated by combining a blue LED with SrGa2S4:Eu (green) and CaS:Eu (red) phosphors for improving the color gamut, which is favorable to full color image.

• Journal of Information Display
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• 제9권2호
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• pp.18-21
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• 2008

We report on white organic light-emitting diodes (WOLEDs) based on single white dopants, $Ir(pq)_2$($F_2$-ppy) and $Ir(F_2-ppy)_2$(pq), where $F_2$-ppy and pq are 2-(2,4-difluorophenyl) pyridine and 2-phenylquinoline, respectively. The similar phosphorescent lifetime of two ligands lead to luminescence emission in two ligands simultaneously. However, the emission color of the devices was reddish, because the energy was not transferred efficiently from the 4,4,N,N'-dicarbazolebiphenyl (CBP) to the $F_2$-ppy ligand, due to the small band gap of the CBP. Accordingly, we used 1,4-phenylenesis(triphenylsilane) (UGH2) with a large band gap, instead of CBP as the host material. As a result, it was possible to adjust the emission color by the host material. The luminous efficiency of the device with $Ir(F_2-ppy)_2$(pq) doped in UGH2 was about 11 cd/A at 0.06 cd/$m^2$.

• 천문학회보
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• 제44권1호
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• pp.75.1-75.1
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• 2019

The universe has been ionized in the post-reionization by several photon contributors. The dominant source to produce the hydrogen ionizing photons is not revealed so far. Faint quasars have been expected to generate UV photon budgets required to maintain ionization state of universe. Observational limits, however, hinder to discover them despite their higher number density than bright one. Consequently, the influence of faint quasars on post-reionization are not considered sufficiently. Therefore, a survey to find faint quasars at z ~ 5 is crucial to determine the main ionizing source in the post-reionization era. Deep images from the Hyper Suprime-Cam Subaru Strategic Program (HSC SSP) allow us to search for quasar swith low luminosities in the ELAIS-N1 field. J band information are obtained by the Infrared Medium-deep Survey (IMS) and the UKIRT Infrared Deep Sky Survey (UKIDSS) - Deep ExtragalacticSurvey (DXS). Faint quasar candidates were selected from several multi-band color cut criteria based on simulated quasars on color-color diagram. To choose the reliable candidates with possible Lyman break, we have performed medium-bands observations. Whether a candidate is a quasar or a dwarf star contamination was decided by results from chi-square minimization of quasar/dwarf model fitting. Spectroscopic follow-up observations confirm three quasars at z ~ 5. 100% spectral confirmation success rate implies that the medium-band observations effectively select faint quasars with strong Lyman alpha emission.

• Korean Journal of Radiology
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• 제21권4호
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• pp.462-470
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• 2020

Objective: To demonstrate that human visual illusion can contribute to sub-endocardial dark rim artifact in contrast-enhanced myocardial perfusion magnetic resonance images. Materials and Methods: Numerical phantoms were generated to simulate the first-passage of contrast agent in the heart, and rendered in conventional gray scale as well as in color scale with reduced luminance variation. Cardiac perfusion images were acquired from two healthy volunteers, and were displayed by the same gray and color scales used in the numerical study. Before and after k-space windowing, the left ventricle (LV)-myocardium boarders were analyzed visually and quantitatively through intensity profiles perpendicular the boarders. Results: k-space windowing yielded monotonically decreasing signal intensity near the LV-myocardium boarder in the phantom images, as confirmed by negative finite difference values near the board ranging -1.07 to -0.14. However, the dark band still appears, which is perceived by visual illusion. Dark rim is perceived in the in-vivo images after k-space windowing that removed the quantitative signal dip, suggesting that the perceived dark rim is a visual illusion. The perceived dark rim is stronger at peak LV enhancement than the peak myocardial enhancement, due to the larger intensity difference between LV and myocardium. In both numerical phantom and in-vivo images, the illusory dark band is not visible in the color map due to reduced luminance variation. Conclusion: Visual illusion is another potential cause of dark rim artifact in contrast-enhanced myocardial perfusion MRI as demonstrated by illusory rim perceived in the absence of quantitative intensity undershoot.

• Journal of the Optical Society of Korea
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• 제19권1호
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• pp.102-111
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• 2015

This paper proposes an algorithm for recovering the colors of objects from multiple near-infrared (near-IR) images. The International Commission on Illumination (CIE) color coordinates of objects are recovered from a series of gray images captured under multiple spectral near-IR illuminations using polynomial regression. The feasibility of the proposed algorithm is tested experimentally by using 24 color patches of the Color Rendition Chart. The experimental apparatus is composed of a monochrome digital camera without an IR cut-off filter and a custom-designed LED illuminator emitting multiple spectral near-IR illuminations, with peak wavelengths near the red edge of the visible band, namely at 700, 740, 780, and 860 nm. The average color difference between the original and the recovered colors for all 24 patches was found to be 11.1. However, if some particular patches with high value are disregarded, the average color difference is reduced to 4.2, and this value is within the acceptability tolerance for complex image on the display.

• 한국습지학회지
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• 제16권2호
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• pp.275-280
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• 2014

수중 암모니아성 질소는 각종 수질오염을 일으키는 물질로서 관리대상이다. 인도페놀법을 변형한 발색대 길이 측정으로 암모니아성 질소를 분석하기 위한 기초 실험을 수행하였다. 1-naphthol을 발색제로 사용한 암모니아성 질소 분석에서 최대 흡광도는 720nm 부근의 파장대에서 관찰되었고, 적정 주입양은 $0.5-1.5m{\ell}$였다. 발색 반응은 신속히 진행되어 20분이 경과하여 전체 최고 흡광도의 80%으로 나타내었고, 발색 시약을 조제하는 과정에서 NaOH 농도는 1.5-2.5M 농도로 설정하였으며, 초기 pH는 영향을 미치지 않았다. 또한, $25^{\circ}C$의 온도에서는 발색대의 길이에 미치는 영향이 미미한 것으로 나타났다.